Vertical White Line In Header

If you wish to make custom stylistic changes to your theme, use the
custom.css template to define custom styles. This way, you will still be able to take advantage of future upgrades to the theme without worrying about overwriting your style changes. Also, be sure you’ve selected the “enable custom stylesheet” option in the Thesis options panel if you wish to use a
custom stylesheet.
On the custom.css template, add the follwing lines:

.full_width > .page {
background: transparent;
}